I would reach out to McIntosh service get their latest version schematic and parts list that your amps can be upgraded to. Also consider purchasing capacitors from them. I had both my MC1000 amps recapped by an authorized Service center near me. The tech there said he had much better luck with restorations sourcing caps through them. I even had the big filter caps replaced. Though he is authorized Mc he services all hi end audio makes.
You might also talk to a tech at audioclassics for their recommendations.
You can always tweak off the beaten path. But why not experience what these amps can do just being refreshed, unless what you have now was already modified out?